A few minutes later, Henry, who was now traveling behind the sled, emitted a low, warning whistle. Bill turned and looked, then quietly
stopped the dogs. To the rear, from around the last bend and plainly into
view, on the very trail they had just covered, trotted a furry, slinking
form. Its nose was to the trail, and it trotted with a peculiar, sliding,
effortless gait. When they halted, it halted, throwing up its head and
regarding them steadi
ly with nostrils that twitched as it caught and
studied the scent of them.

He was ___ them
A encouraging
B following
C mimicking
D ignoring